TECHNICAL FIELD
[0001] The present disclosure generally relates to compression devices, and in particular
to pumping fluid to and from compression devices.
BACKGROUND
[0002] Intermittent pneumatic compression (IPC) devices are used to improve circulation
and minimize the formation of thrombi in the limbs of patients by applying compression
treatment to the limb through a series of compression cycles. A compression garment
that can be worn on a limb of a patient includes one or more inflatable bladders positioned
to apply compression to the limb when the garment is being worn and one or more bladders
in the garment are inflated. Some compression devices include pumps that use solenoid
valves to deliver pressurized fluid to the bladder in the garment. Diaphragm pumps
require an electric motor and other associated mechanical mechanisms to convert rotational
motion into reciprocating motion of a diaphragm. One reason these types of pumps are
used for compression devices is that their relatively high flow rates (between about
3-5 slpm at 1 psi of backpressure) are generally sufficient to meet the fluid flow
demands of a conventional compression garment.
[0003] A single pump is most commonly mounted in a controller that is separate from the
compression garment. The controller is typically mounted on a bed or other support
next to the patient and tubing carries the compressed air from the controller to the
garment. The tubing can be at a minimum a nuisance and may also lead to a loss of
full function of the compression device if the tubing becomes kinked or is laid upon
by the patient.
SUMMARY
[0004] In a first aspect, a compression device may generally comprise a compression garment
positionable on the limb of the wearer and including an inflatable bladder for providing
compression treatment to the limb. A pump assembly may be supported by the compression
garment. The pump assembly may be in fluid communication with the bladder for pressurized
fluid delivery. The pump assembly may comprises at least first and second pumps. Passaging
may connect each of the first and second pumps for fluid communication with the inflatable
bladder.
[0005] In said first aspect, the pumps may be plumbed to each other in at least one of a
parallel configuration and a series configuration.
[0006] In said first aspect, a valve may be in fluid communication with each of the first
and second pumps. The valve may be operable to selectively connect the first and second
pumps in fluid communication with one another in parallel and to selectively connect
the first and second pumps in fluid communication with one another in series.
[0007] In said first aspect, a controller may be supported by the compression garment, the
controller controlling the valve.
[0008] In said first aspect, the controller may be configured to fluidly connect the first
and second pumps in parallel when a pressure in the inflatable bladder is equal to
or below a predetermined threshold and to fluidly connect the first and second pumps
in series when the pressure in the inflatable bladder exceeds the predetermined threshold.
[0009] In said first aspect, the pump assembly may further comprise a third pump in fluid
communication in parallel with the first pump. The valve may be adapted to selectively
fluidly connect the first and third pumps in fluid communication in series with the
second pump and to selectively connect the first and third pumps in fluid communication
in parallel with the first pump.
[0010] In said first aspect, a controller may control the valve.
[0011] In said first aspect, the first and second pumps may each comprise a housing defining
an inlet manifold and an outlet manifold. A nipple may project from one of the inlet
and outlet manifolds. A first port may communicate with the inlet manifold and a second
port may communicate with the outlet manifold. The nipple of the first pump may be
adapted for selective sealing reception in the first port of the second pump and in
the second port of the second pump.
[0012] In said first aspect, the first and second pumps may each be piezoelectric pumps.
[0013] In a second aspect, a method of delivering pressurized fluid to a compression garment
may generally comprise operating at least two pumps of a pump assembly during a compression
cycle in a first configuration for delivering pressurized fluid to a compression garment
during the compression cycle for compressing a part of a wearer's body. During the
compression cycle, the first arrangement may be changed so that the at least two pumps
are arranged in a second arrangement, different from the first arrangement, for delivering
pressurized fluid to the compression garment.
[0014] In said second aspect, in the first configuration, the at least two pumps may be
arranged in one of series and parallel and, in the second configuration, the at least
two pumps may be arranged in the other of series and parallel.
[0015] In said second aspect, operating the pumps in parallel when a pressure in the compression
garment is equal to or below a predetermined threshold and operating the pumps in
series when the pressure exceeds the predetermined threshold.
[0016] In said second aspect, the predetermined threshold may be about 60 mmHg.
[0017] In said second aspect, operating the at least two pumps in the first configuration
may comprise moving a valve to one position and operating the at least two pumps in
the second configuration may comprise moving the valve to another position different
from said one position.
[0018] In said second aspect, in the first configuration, two pumps of the pump assembly
may be arranged in parallel, and in the second configuration the two pumps may be
placed in fluid communication with a third pump such that the two pumps in parallel
are arranged in series with the third pump.
[0019] In said second aspect, operating the pumps in the first configuration when a pressure
in the compression garment is below about 50 mmHg, and operating the pumps in the
second configuration when the pressure in the inflation garment exceeds about 50 mmHg.
[0020] In a third aspect, a modular pump assembly for use in a compression device may generally
comprise a first modular pump including a housing defining an inlet manifold and an
outlet manifold. A pumping unit may be disposed for receiving fluid from the inlet
manifold and exhausting fluid into the outlet manifold. A nipple may project from
one of the inlet and outlet manifolds. A first port may communicate with the inlet
manifold and a second port may communicate with the outlet manifold. A second modular
pump may include a housing defining an inlet manifold and an outlet manifold. A pumping
unit may be disposed for receiving fluid from the inlet manifold and exhausting fluid
into the outlet manifold. A nipple may project from one of the inlet and outlet manifolds.
A first port may communicate with the inlet manifold and a second port may communicate
with the outlet manifold. The nipple of the first pump may be adapted for selective
sealing reception in the first port of the second pump or in the second port of the
second pump. The nipple of the second pump may be adapted for selective sealing reception
in the first port of the first pump or in the second port of the first pump.
[0021] In said third aspect, the first pump may comprise a valve located in one of the first
and second ports thereof and the second pump may comprise a valve located in one of
the first and second ports of the second pump.
[0022] In said third aspect, the valve of the second pump may be disposed in the second
port of the second pump. The nipple of the first pump may be configured to open the
valve of the second pump upon insertion of the nipple of the first pump into the second
port of the second pump, placing the outlet manifold of the first pump in fluid communication
with the outlet manifold of the second pump.
[0023] Other objects and features will be apparent from the drawings and description and
from the claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0024]
Fig. 1 is a block diagram of a compression device.
Fig. 2 is a schematic of a modular pump of the compression device of Fig. 1.
Fig. 3A is a schematic of a modular pump assembly including two modular pumps in series.
Fig. 3B is a schematic of a modular pump assembly including two modular pumps in parallel.
Fig. 4 is a schematic of an out-of-plane configuration of a modular pump.
Fig. 5 is a graph illustrating flow rate of various pump assemblies over a pressure
range.
Figs. 6A-6E are schematics of different pump arrangements.
Fig. 7 is a graph illustrating flow rate of various pump assemblies over a pressure
range.
Fig. 8A is a schematic of a two-pump assembly including a three way valve in communication
with the pumps.
Fig. 8B is a schematic of a three-pump assembly including a three way valve in communication
with the pumps.
[0025] Corresponding reference characters indicate corresponding parts throughout the drawings.
DETAILED DESCRIPTION
[0026] Referring to Figs. 1-2, a compression device 11 applies repeated, sequential compression
therapy to a limb of a wearer. The compression device 11 includes a garment 13 sized
and shaped to be wrapped around a leg or other limb of the wearer. A pump assembly
15 is fluidly connected to the garment 13 through conduit 17 for selectively pressurizing
a bladder 19 of the garment by introducing gas (e.g., air) into the bladder. A controller
21 includes a processor 23 operatively connected to the pump assembly 15 for controlling
the pressurization of the garment 13. A pressure sensor 25 is operatively connected
to the processor 23 and coupled to the bladder 19 through the conduit 17 for measuring
pressure in the bladder. Although a single bladder 19 is illustrated, the garment
13 can have two or more bladders. Moreover, while the conduit 17 and the controller
21 are shown as being incorporated into the garment 13, a controller and/or tubing
may be separate from the garment and bladder.
[0027] The modular pump assembly 15 may include two or more modular pumps 31, one of which
is schematically illustrated in Fig. 2. The modular pump includes a first port 33
leading to an inlet manifold 35, a pumping unit 37 in fluid communication with the
inlet manifold, an outlet manifold 39 in fluid communication with the pumping unit,
and an outlet including a nipple 41. A second port 43 is located in the outlet manifold
39 on an end opposite the outlet nipple 41. A valve 45 can be disposed in the outlet
manifold 39 to prevent fluid from escaping (or entering) the outlet manifold through
the second port 43, as will be explained in greater detail below. The modular pump
31 can be micro pump, such as a piezoelectric pump, capable of about 1 slpm of flow
under a backpressure of about 1 psi. Additionally or alternatively, the modular pump
31 can be another type of micropump (e.g., diaphragm, gear, piston, peristaltic, electroosmotic,
electrohydrodynamic, magnetic, etc.). Moreover, it should be appreciated that that
modular pump 31 can be a type of pump that is not a micropump. Still further, the
pumps are shown as modular (e.g., Figs. 3A-4), non-modular pumps may be used such
that the pumps may be plumbed together in a fixed arrangement.
[0028] Conventional compression devices typically use diaphragm pumps capable of between
about 3-5 slpm of flow at 1 psi of backpressure. However, a single modular pump, which
cannot operate in this range, may not be sufficient to meet the pressure requirements
of a conventional compression device. To meet these pressure requirements, multiple
modular pumps are combined to dynamically increase the overall flow rate of the pumps
in a scalable and/or incremental manner. The modular pumps 31 can be combined in a
variety of ways. For example, the pumps 31 can be combined in series such that an
outlet nipple 41 of a first pump P1 is connected to the first port 33 of a second
pump P2 (Figs. 3A and 6A). As another example, the pumps 31 can be combined in parallel
such that the outlet nipple 41 of the first pump is connected to the second port 43
of the second pump (Figs. 3B and 6B). The valve 45 of the second pump P2 prevents
fluid from escaping the second port 43 when the pumps are connected in series. The
valve can be an elastomeric (e.g., silicone) membrane which has slits such that insertion
of nipple 41 opens the valve for pneumatic communication. Any number of pumps can
be combined in series and/or parallel subject to the structural and operational limits
of the pump design. The pumps are shown such that manifolds are "in-plane" (i.e.,
inlet and outlet of the pump extend in the same direction). However, the pumps could
be configured such that the manifolds of a given pump are out of plane. In the out
of plane configuration, the outlet 41 of a pump 31 can be turned to be, for example,
orthogonal to the inlet 33 (Fig. 4). In other examples, the outlet 41 can be disposed
relative to the inlet 33 at an angle other than 90 degrees. This out of plane configuration
can, for example, make combining the pumps easier and provide a more compact pump
assembly.
[0029] Referring now to Figure 5, an experimentally determined comparison of flow rate versus
pressure for a single modular pump and various series and parallel pump combinations
is shown. Generally, combining the pumps in series increases the operating range of
the pumps (i.e., the pumps will operate at a higher backpressure than a single pump),
but does not increase the maximum flow rate. However, the flow rate from the combined
pumps in series does not diminish at increasing backpressure at the same rate as for
a single pump so that higher flow rates may be attained through the range between
the boundaries. Combining the pumps in parallel does not increase the overall pressure
range of operation of the pump assembly as compared to a single pump, but increases
the maximum flow output at lower backpressures. As shown in Fig. 5, the maximum output
is nearly doubled for combined pumps in parallel as compared to a single pump, and
remains higher at each pressure in the range until the maximum operating backpressure.
Thus, in general, running the pump assembly in parallel increases the pneumatic output
of the pump assembly at lower pressures, while at higher backpressures it is more
beneficial to run the pump assembly in series.
[0030] As mentioned above, the pump assembly 15 can have configurations other than the two-pump
series and parallel arrangements described above. For example, the pump assembly 15
may include three or more pumps arranged in various series and parallel configurations.
Figure 6C shows a three-pump circuit including a first pump P1, a second pump P2,
and a third pump P3. The first pump P1 is in series with pump P2. The series pumps
P1, P2 are then together arranged in parallel with pump P3. Figure 5 shows that this
configuration provides increased flow capacity in comparison to the two-pump configurations
and the single pump over the entire working range of the pump assembly.
[0031] Figure 6D shows a three-pump circuit including two pumps P1, P2 in parallel with
each other. An output manifold of the two pumps is in series with a third pump P3.
[0032] Figure 6E shows a three-pump circuit including a first pump P1 in series with an
inlet manifold of second and third pumps P2, P3 which are in parallel with each other.
[0033] Fig. 7 shows the experimentally determined flow rates of the pump circuits shown
in Figs. 6A, 6B, and 6D over a pressure range of 0-200 mmHg. Fig. 7 also shows flow
profiles for the pump circuit shown in Fig. 6D with the third pump P3 in various operating
configurations (off, 12V, 18V, 25V). The results shown in Fig. 7 indicate that, depending
on the fluid pressure in the device, it may be desirable to use different pump arrangements
to maximize flow output.
[0034] To take advantage of the varying fluid flow capabilities of the disclosed configurations,
it is possible to construct a pump assembly that can switch between the disclosed
configurations. For instance, a valve 51 (Fig. 8A) can be disposed in fluid communication
between first and second pumps P1, P2 to selectively place pump P1 in series or in
parallel with pump P2. The valve 51 can be switched to a first position where the
outlet of pump P1 is fluidly connected to the inlet of pump P2 (series), or to a second
position where the outlet of P1 is fluidly connected to an outlet of P2 via the second
inlet (parallel). In the illustrated embodiment, the valve 51 is a 3-way/3-position
piezo valve. A check valve 52 prevents the pneumatic output of P1 from being lost
to the environment when pump P1 is in series with pump P2.
[0035] Referring to Fig. 7, it can be seen that a transition point TP2 indicates the pressure
level where the performance of the two-pump parallel configuration falls below the
two-pump series configuration.
[0036] The valve 51 can also be used to switch between the arrangements shown in Figs. 6B
and 6D (see Fig. 8B). In the pump assembly configuration shown in Fig. 8B, first and
second pumps P1, P2 are arranged in parallel and the valve 51 is disposed between
the outlet of P1 and P2 and a third pump P3. The valve 51 can be switched to a first
position where the outlet of P1 and P2 is fluidly connected to an outlet passage 53
bypassing P3 so that that the pump assembly is arranged in the two-pump parallel configuration
shown in Fig. 6B. This configuration presupposes that P3 is turned to an off position.
If P3 is turned on then the three pumps P1, P2, P3 will all be arranged in parallel.
The valve 51 can also be switched to a second position where the outlet of P1 and
P2 is fluidly connected to the inlet of P3, placing P3 in series with P1 and P2 and
producing the pump assembly shown in Fig. 6D.
[0037] Referring to Fig. 7, it can be seen that a transition point TP1 indicates the pressure
level where the performance of the two-pump parallel configuration in Fig. 6B falls
below the configuration in Fig. 6D.
[0038] Therefore, during operation of the compression device 11, the processor 23 can operate
the pump assembly 15 to switch between the various pump arrangements to optimize flow
output over the entire pressure range based on feedback from the pressure transducer.
[0039] Referring again to the arrangement of Fig. 8B, as compression treatment is initiated
(bladder pressure=0) and fluid is pumped into the bladder 19, the processor 23 can
switch the valve 51 to the first position, placing pumps P1, P2 in parallel and bypassing
pump P3 so that the device 11 is operating at an optimal flow capacity as pressure
increases from 0 mmHg (Fig. 7). Once the processor 23 determines that the pressure
sensor 25 has measured a pressure in the bladder 19 exceeding a predetermined threshold
(e.g., about 50 mmHg), the processor 23 can switch the valve 51 to the second position,
placing pumps P1 and P2 in series with pump P3 for superior performance in the higher
pressure range. In summary, operation of the device 11 where the pressure in the bladder
19 is between about 0 and about 50 mmHg (or initiation of a new cycle) causes the
processor 23 to switch the pump assembly 15 to the two-pump parallel arrangement shown
in Fig. 6B, and operation of the device where the pressure in the bladder exceeds
about 50 mmHg causes the processor to switch the pump assembly to the three-pump parallel/series
configuration shown in Fig. 6D. It will be understood that this can be achieved by
operating the valve 51 shown in Fig. 8B. As a result, flow output is optimized during
the entire compression cycle for this pump assembly.
[0040] By way of another example, if the pump assembly has the configuration shown in Fig.
8A, where the valve 51 is between pumps P1 and P2, as compression treatment is initiated
(pressure=0) and fluid is pumped into the bladder 19, the processor can switch the
valve 51 to the second position placing the pumps P1, P2 in parallel so that the device
11 is operating at an optimal (high) flow capacity as pressure increases from 0 mmHg
(Fig. 7). The pressure sensor 25 monitors the pressure in the bladder 19 as compression
treatment is continued. Once the processor 23 determines that the pressure sensor
25 has measured a pressure in the bladder 19 that exceeds a predetermined threshold
(e.g., 60 mmHg), the processor 23 can switch the valve 51 to the first position placing
the pumps P1, P2 in series. The changeover occurs about at the point labeled TP2 in
Fig. 7. Thus, operation of the device 11 where the pressure in the bladder 19 is between
about 0 and about 60 mmHg (or upon initiation of the new cycle) causes the processor
23 to switch the pump assembly 15 to the parallel arrangement (Fig. 6B), and operation
of the device where the pressure in the bladder exceeds about 60 mmHg signals to the
processor to switch the pump assembly to the series arrangement (Fig. 6A). The changeover
occurs approximately where transition point 2 (TP2) is identified on Fig. 7. It is
to be understood that the change in configuration between Figs. 6B and 6A can be achieved
by operation of the valve 51 shown in Fig. 8A. As a result, flow output is optimized
during the entire compression cycle. Other possible ways of controlling or setting
the configuration of the pumps may additionally or alternatively be used. In Fig.
7, four results for using two pumps in parallel with each other in combination with
a third pump in series are shown. The difference between these four results is the
operating strength of the third pump (i.e., 0V, 12V, 18V or 25V).
[0041] Modifications and variations are possible without departing from the scope of this
disclosure.
[0042] When introducing elements in the present disclosure, the articles "a", "an", "the"
and "said" are intended to mean that there are one or more of the elements. The terms
"comprising", "including" and "having" are intended to be inclusive and mean that
there may be additional elements other than the listed elements.
[0043] In view of the above, it will be seen that the several objects are achieved and other
advantageous results attained.
[0044] As various changes could be made in the above constructions and methods without departing
from the scope of the disclosure, it is intended that all matter contained in the
above description and shown in the accompanying drawings shall be interpreted as illustrative
and not in a limiting sense.
1. A compression device comprising:
a compression garment positionable on the limb of the wearer, the garment comprising
an inflatable bladder for providing compression treatment to the limb;
a pump assembly supported by the compression garment, the pump assembly in fluid communication
with the bladder for pressurized fluid delivery, the pump assembly comprising at least
first and second pumps; and
passaging connecting each of the first and second pumps for fluid communication with
the inflatable bladder.
2. A compression device as set forth in claim 1 wherein the pumps are plumbed to each
other in at least one of a parallel configuration and a series configuration.
3. A compression device as set forth in claim 2 further comprising a valve in fluid communication
with each of the first and second pumps, the valve operable to selectively connect
the first and second pumps in fluid communication with one another in parallel and
to selectively connect the first and second pumps in fluid communication with one
another in series.
4. A compression device as set forth in claim 3 further comprising a controller supported
by the compression garment, the controller controlling the valve.
5. A compression device as set forth in claim 4 wherein the controller is configured
to fluidly connect the first and second pumps in parallel when a pressure in the inflatable
bladder is equal to or below a predetermined threshold and to fluidly connect the
first and second pumps in series when the pressure in the inflatable bladder exceeds
the predetermined threshold.
6. A compression device as set forth in claim 3 wherein the pump assembly further comprises
a third pump in fluid communication in parallel with the first pump, the valve being
adapted to selectively fluidly connect the first and third pumps in fluid communication
in series with the second pump and to selectively connect the first and third pumps
in fluid communication in parallel with the first pump.
7. A compression device as set forth in claim 6 further comprising a controller for controlling
the valve.
8. A compression device as set forth in any preceding claim wherein the first and second
pumps each comprise a housing defining an inlet manifold and an outlet manifold, a
nipple projecting from one of the inlet and outlet manifolds, and a first port communicating
with the inlet manifold and a second port communicating with the outlet manifold,
the nipple of the first pump being adapted for selective sealing reception in the
first port of the second pump and in the second port of the second pump.
9. A compression device as set forth in any preceding claim wherein the first and second
pumps are each piezoelectric pumps.
10. A method of delivering pressurized fluid to a compression garment, the method comprising:
operating at least two pumps of a pump assembly during a compression cycle in a first
configuration for delivering pressurized fluid to a compression garment during the
compression cycle for compressing a part of a wearer's body; and
during said compression cycle, changing said first arrangement so that the at least
two pumps are arranged in a second arrangement, different from the first arrangement,
for delivering pressurized fluid to the compression garment.
11. The method of claim 10 wherein, in the first configuration, the at least two pumps
are arranged in one of series and parallel and, in the second configuration, the at
least two pumps are arranged in the other of series and parallel.
12. The method of claim 11 further comprising operating the pumps in parallel when a pressure
in the compression garment is equal to or below a predetermined threshold and operating
the pumps in series when the pressure exceeds the predetermined threshold.
13. The method of claim 12 wherein the predetermined threshold is about 60 mmHg.
14. The method of claim 10 wherein operating the at least two pumps in the first configuration
comprises moving a valve to one position and operating the at least two pumps in the
second configuration comprises moving the valve to another position different from
said one position.
15. The method of claim 10 wherein, in the first configuration, two pumps of the pump
assembly are arranged in parallel, and in the second configuration the two pumps are
placed in fluid communication with a third pump such that the two pumps in parallel
are arranged in series with the third pump.